Strange lump/weight loss

Hi all,
I've lost about 15 pounds or so since late Sept. Nothing compared to some of you, I know, but my appetite has become increasingly puny. I also brushed across a strange lump on my left outer thigh in January. I went to my new primary care doc, who didn't seem particularly concerned by it. Between that and the weight loss, she suggested I return to get blood work done and keep a food diary.
I go back on Monday.
The lump is odd. It's painless, firm and can be rather sizable at night when I lay down. Enough of a roundedness to it that I can cup my hand around it. When I'm seated or up during the day, it's only palpable if you really push and search for it. And when I was at my GP;s office, it wasn't very prominent. I think it'll behave the same on Monday.
I showed it to my acupuncturist last week. She said it was too firm and large to be a fatty deposit, but she though it might be a muscle spasm, though she did mention it should be sore if that's the case. That sounded very odd and nonsensical to me to be a muscle spasm that's lasted at least a month and a half, but...
I go back to my primary care doc on Monday for a complete blood panel and for her to look at the lump again. I called my GI nurse this morning to have them fax over my last blood info drawn in Sept which showed lowered iron and elevated inflammatory markers. She called me back at 3:30 today and said my GI wanted my blood drawn TODAY b/c of the weight loss. I declined since I'm going Monday and they'll do a more thorough workup that they can share with the GI. (Didn't want suspicious insurance companies butting in).

Anyway, any thoughts on the weight loss since Sept or the lump on my leg? I don't even know what kind of doc I should be seeing. Dermatologist? Oncologist? GP?

Of course, I googled it and one of the rare possibilities is a sarcoma, which is a cancerous tumor. The lump coupled with weight loss and decreased appetite is surely scaring me.

Any thoughts or insights would be appreciated.

Thanks so much, gumyby44. It has really been frightening. I have a 5 and 11-year-old and was laid off from a job 3 years ago after nearly 20 years there. I go for bloodwork Monday. And would appreciate good thoughts and/or prayers.